panic: BLOCKED to LOADED with usecount 2 at vrelel:LINE

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 9e59b38ee44e Catch up with MI pci changes.
git tree: netbsd
console output: https://syzkaller.appspot.com/x/log.txt?x=146687f3200000
dashboard link: https://syzkaller.appspot.com/bug?extid=3489cc4ed73e9d4a5106

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+3489cc...@syzkaller.appspotmail.com

[ 428.5802065] panic: BLOCKED to LOADED with usecount 2 at vrelel:783
[ 428.5902787] cpu1: Begin traceback...
[ 428.5902787] vpanic() at netbsd:vpanic+0x214
[ 428.6003626] vstate_assert_get() at netbsd:vstate_assert_get
[ 428.6205266] vstate_assert_change() at netbsd:vstate_assert_change+0x213
[ 428.6306088] vrelel() at netbsd:vrelel+0x36c
[ 428.6406905] change_root() at netbsd:change_root+0x68
[ 428.6507733] sys_chroot() at netbsd:sys_chroot+0x10a
[ 428.6608566] sys___syscall() at netbsd:sys___syscall+0xe2
[ 428.6709374] syscall() at netbsd:syscall+0x32e
[ 428.6810185] --- syscall (number 198) ---
[ 428.6810185] 7c60dbc3f4aa:
[ 428.6911016] cpu1: End traceback...

[ 428.6911016] dumping to dev 4,1 (offset=0, size=0): not possible
[ 428.7011832] rebooting...
SeaBIOS (version 1.8.2-20190204_181744-google)
Total RAM Size = 0x00000001e0000000 = 7680 MiB
CPUs found: 2 Max CPUs supported: 2
found virtio-scsi at 0:3
virtio-scsi vendor='Google' product='PersistentDisk' rev='1' type=0
removable=0
virtio-scsi blksize=512 sectors=4194304 = 2048 MiB
drive 0x000f2a00: PCHS=0/0/0 translation=lba LCHS=520/128/63 s=4194304
Booting from Hard Disk 0...

>> NetBSD/x86 BIOS Boot, Revision 5.10 (Tue Jul 17 14:59:51 UTC 2018) (from
>> NetBSD 8.0)
>> Memory: 639/3144640 k

1. Boot normally
2. Boot single user
3. Disable ACPI
4. Disable ACPI and SMP
5. Drop to boot prompt
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open /var/db/entropy-file
WARNING: 1 module failed to load


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[Maxime Villard]

Seems to be a one-off. There have been locking fixes in this area since, so
likely fixed and not triggerable anymore.

#syz invalid